Differential shrinkage yarn



United States Patent 3,416,302 DIFFERENTIAL SHRINKAGE YARN Robert H. Knospe, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 608,281, Jan. 10, 1967. This application Sept. 12, 1967, Ser. No. 667,095

51 Claims. (Cl. 57-140) ABSTRACT OF THE DISCLOSURE A yarn comprising a plurality of differentially shrin-kable drawn continuous filaments including a high shrinkage group of filaments and a lower shrinkage group of filaments, the filaments of each said group being constituted by a polycarbonamide wherein at least 50 mol percent of the repeating units are of the formula:

wherein x represents 1 or 2, y represents an integer in the range of 7-14 and R represents the same or different member of the class consisting of hydrogen and methyl, said yarn being typified by exhibiting a DFL greater than 1.0% after being subjected to a load of 4 mg. per denier during boil-off and increasing at least 0.5% in DFL after being subjected to heat-setting at 177 C. for two minutes under the same total load. These yarns yield attractive fabrics of excellent bulk and covering power, and increase in bulk upon heat-setting.

This application is a continuation-in-part of my application Ser. No. 608,281 filed Jan. 10, 1967, and now abandoned.

BACKGROUND OF THE INVENTION Field of the invention.In recent years, the introduction of synthetic yarns such as those from polyamides has led to fabrics having high strength, improved resistance to wear and in some cases improved launderability and wrinkle resistance. However, fabrics made from these yarns, particularly the continuous filament yarns, tend to have a slick, cold hand and are deficient in covering ability and luster in many end uses. Thus, in spite of their superior functional properties, fabrics produced from these yarns do not have the desirable aesthetic qualities of silk fabrics such as a warm, dry hand and good luster. Improvements in aesthetics have been attained with mixed shrinkage yarns. When the resulting fabric is heated, e.g., with hot or boiling water, some of the filaments shrink more than the others, thus giving the fabric greater bulk as well as improved hand. However, it is difficult to obtain a mixed shrinkage yarn which has a desirable balance of properties, i.e., a relatively high shrinkage differential between the high and low shrinkage filaments, relatively low total yarn shrinkage, freedom from tendency to form filament loops as initially produced for ease of processing into fabric and good functional properties. Mixed shrinkage polyamide yarns in which the shrinkage differential increases upon heat setting were not available to the prior art before the instant invention.

The prior art.U.S. 3,225,534 issued Dec. 28, 1965, to R. H. Knospe discloses and claims mixed shrinkage yarns which by virtue of carefully regulated processing possess a reasonable difference in shrinkage among the filaments and, at the same time, are free from objectionable loopiness when removed from the package for processing into fabric. However, heat setting of the Knospe yarn proice duces no substantial increase in bulk or differential shrinkage of the yarn. Further, while the Knospe invention provides a commercially attractive route to the production of very desirable fabrics, larger differences in shrinkage are needed to produce a more bulky yarn. It is therefore very desirable to have a mixed shrinkage yarn which may be heat treated to reduce the overall yarn shrinkage while increasing the difference in shrinking among the filaments. Furthermore, it is particularly important to have a mixed shrinkage yarn which develops a good degree of shrinkage difference under appreciable load so that the desired bulk may be achieved under the restraints existing in the fabric and those imposed in fabric finishing procedures.

SUMMARY OF THE INVENTION The yarn of the present invention comprises a plurality of continuous, oriented polycarbonamide filaments selected from at least two groups of different shrinkage. The filaments consist of polycarbonamides, wherein at least 50 mol percent of the repeating units are of the formula R R I wherein x is 1 or 2, y is an integer in the range of 7-14, R is the same or different member of the class consisting of hydrogen and methyl. The yarns of the invention when subjected to boiling water exhibit a DFL greater than 1.0% under a load of 4 mg.d., and increasingat least 0.5 in DFL when subjected to heat setting as described below.

Thus one of the aforesaid groups of filaments in the yarn comprise a high shrinkage group and the other, a low shrinkage group. Their selection will be described in more detail below.

The diamino portion of Formula I due to its carbocyclic nature, is a mixture of isomers having trans-trans (tt), cis-trans (ct), and cis-cis (cc) configurations. Hydrogenation conditions employed in preparing the diamines used in the polymer synthesis results in a mixture of isomers, different conditions of hydrogenation producing a different isomer distribution as shown in US. 2,494,563 and US. 2,606,924.

In a preferred embodiment, the different groups of filaments in the yarn are provided by combining a first group of filaments consisting essentially of a polycarbonamide having repeating units of Formula I and a second group of filaments consisting of a polyamide containing from 50 to mol percentage of the repeating units of Formula I and 5 to 50 mol percentage of another polyamide unit prepared from a member of a class consisting of (1) the same diamine as employed for production of the Formula I repeat unit with a different dicarboxylic acid and (2) the same dicarboxylic acid as employed for production of the Formula I repeat unit with the different diamine.

In another embodiment, both groups of filaments are constituted by polymers which consist essentially of the units of Formula I, there being substantially less, i.e., at least about 10% by weight less of the trans-trans, cistrans or cis-cis diamino units in the polymer units of the polycarbonamide constituting the second group of filamerits than in the polycarbonamide constituting the first group of filaments.

In another embodiment, both groups of filaments are prepared from polymers which consist essentially of the units of Formula I, the second group of filaments being constituted by polycarbonamide having a lower relative viscosity, i.e., at least about 9 units less than the polycarbonamide constituting the first group of filaments.

length is then determined again and the percent shrinkage calculated from the equation 100(L L o where L, equals length of skein before boiling, L equals length of skein after boiling.

The percent difference in filament length (DFL) between the high and low shrinkage filaments is determined as follows: A strand of yarn such as a representative 40- centimeter strand, containing both high and low shrinkage filaments, is separated from the boiled and dried skein, cut at each tie point, doubled and the free ends tied together to form a loop. The free ends above the knot are taped to a meter rule and the length of the in dividual filament loops measured by hanging a 0.6 g. paper clip in each loop. At least low shrinkage and 5 high shrinkage filaments are measured in this manner. The percent DFL is calculated from the following equation:

where L is the average length of the longer filaments and L is the average length of the shorter filaments.

The DFL after exposure to heat setting temperature is measured by hanging a similarly boiled-off, air dried skein in an oven at 177 C. for 2 minutes under the same total load as was used in boil-off and then determining the DFL as described above for the boiled-oif skein.

The expression relative viscosity as used herein signifies the ratio of the flow time in a viscometer of a polymer solution relative to the flow time of the solvent by itself. Measurements of relative viscosities as referred to herein and as measured in the examples is determined from a solution of 3.7 grams of polyamide in 50 ml. of a 1:1 mixture of 98100% formic acid and phenol at 25 C., unless otherwise noted.

Orientation index, as referred to hereinbefore, is measured on the high and low shrinkage filaments separately by means of flat-plate wide-angle X-ray diffraction patterns. The oriented fibers, spun and drawn as described herein, show a unique diffraction feature consisting of a well-defined meridional reflection which occurs at a Bragg spacing of about 11.4 A. for polymers prepared with dodecanedioic acid and at slightly different spacings for polymers of different unit lengths. The existence of this well defined meridional spot allows the development of the orientation parameter, herein called the orientationindex, in samples of widely varying degrees of crystallinity. This orientation index is obtained by measuring the peak or maximum intensities of this meridional diffraction spot and that of the equatorial diffraction, or amorphous halo, found at the Bragg spacing of about 4.7 A. This index is calculated as the ratio of the meridional spot of maximum intensity divided by the maximum intensity of the equatorial region. The intensities are measured on the X-ray negatives using conventional microphotometry techniques. The diffraction patterns are obtained in a conventional manner on a sample of the yarn taking care to assure that all of the filaments in the yarn are aligned in an exactly parallel fashion. A sample thickness of no more than 20 mils is used with a sample to film distance of 7.5 cm. Exposure times for the X-ray negatives should be such that the microphotometer registers optical densities not exceeding 1.0 and not less than 0.10. Analysis of both regions must be made on the same X-ray negative. Careful microphotometer technique must be employed to be certain of measuring the maximum densities in both the meridional and equatorial directions and also in order to compute the proper background correction pertinent to each trace, which is subtracted from the total density prior to calculating the orientation index.

Ordinarily, the yarn of the invention will consist of about an equal amount (by wgt.) of high and low shrinkage filaments. These proportions can of course be varied.

Percent Shrinkage, S

Percent DFL= As a rule, the higher the difference in shrinkage, the lower the weight percentage of high shrinkage filaments required to produce meaningful results in fabric. A minimum of about 10% by weight of high shrinkage filaments is believed necessary for the yarn to display the desired effect. Within the range of shrinkage differential of about 1.5% to about 10%, at least about 25% by weight of each (the high and low shrinkage) component is preferred. To improve yarn stability, i.e., to keep coring (migration and aggregation of the high shrinkage component) and/0r cracking (separation of components) to a minimum when yarn shrinkage occurs, the filaments of the yarn should be cospun or intimately interlaced.

In the examples which follow the amounts of cis-cis isomer did not vary greatly from about 5%, thus giving the trans-trans content of any isomer mixture, effectively identifies it.

THE EXAMPLES Example 1 A polymer is prepared in an autoclave containing 50 parts water and 50 parts of the salt of bis-(4-aminocyclohexyl)methane and dodecanedioic acid. The diamine consists of 70% of the tt isomer.

As a viscosity stabilizer, 12 millimoles of acetic acid are added for each mole of the polyamide salt. The solution also contains 0.005% manganous hypophosphite, based on the weight of the salt. This solution is heated under 350 p.s.i. for 2 hours while the temperature is raised a sufficient amount of a 20% aqueous slurry of finely-divided kaolinite being added when the temperature reaches 210 C. to provide a concentration of 2% by weight of the kaolinite in the final polymer. The pressure is then reduced to atmospheric while the temperature is raised to 315 C. and the polymer held under 14.3" vacuum for 1 hour. It is then extruded and cut to flake. The relative viscosity of the flake is 45.9.

In a similar fashion, a copolymer is prepared from a salt of bis-(4-aminocyclohexyl)methane and a mixture of dodecanedioic and isophthalic acids. The mixed acids contain 8.7% -by weight of isophthalic acid which is sufficient to provide 10% by weight or 12.3 mole percent of the isophthalic copolymer component in the final polymer. The diamine contains 70% of the tt isomer and 6.8 millimoles acetic acid per mole of salt is used. The relative viscosity of the flake is 52.5.

The polymer and copolymer are melted separately at 325 C. in screw type melters. They are then extruded simultaneously through different holes in the same spinneret at 325 C. to form 34 trilobal filaments (17 from each polymer), as described in U.S. 3,225,534. The relative viscosity of the homopolymer filaments is 36.2 while that of the copolymer filaments is 34.7. The filaments from the two polymers are quenched and' then passed over a finish applicator roll where a conventional lubricating finish is applied. The filaments then pass to a pair of power-driven feed rolls rotating at a peripheral speed of 800 yds./min. After the feed rolls, the yarn passes around a draw pin heated at C. and then to a pair of draw rolls having a peripheral speed of 1680 yds./min. and heated to 120 C. The yarn then passes to a pair of annealing rolls rotating at a peripheral speed of 1680 yds./ min., the yarn being heated at ISO- C. on these rolls. The yarn is then interlaced to provide a cohesive filament bundle as described by Bunting and Nelson in US. 2,985,995. The yarn is then passed to a pair of unheated rolls, rotating at a peripheral speed of 1689 yds./min., and is then wound into a package in the conventional manner at 1650 yds./min. The yarn is given six passes around the feed rolls, eight passes around the draw and annealing rolls, and six passes around the final unheated rolls. The denier of the final yarn is 63. The shrinkage of the yarn in boiling water with 4 mg.d. load is 9.4% and the DFL is 5.7%. When the yarn is boiled off under 4 mg.d. load and heat-set at 177 C. under the same total load, the yarn shrinkage is 32% and the DFL is 34.5%.

mild mechanical treatment may, for instance, consist of striking, rubbing, brushing, or vibrating. Such treatment during the electrical treatment will not only fold out but also spread the material out.

At this point in the flow sheet of FIGURE 1 the sheet material is in a spread-out condition wherein the individual fibrils, making up the material, are parallel to the longitudinally axis of the sheet material. In many cases, and for many applications, this is a desirable configuration. However, for certain textile products the yarn used in the manufacture therein should not be lean and smooth but rather should have a high percentage of loose-fibrils along the surface of the web or sheet as the case may be. For instance, in the case of blankets, carpets, and fabrics made from woolen yarns, it is essential to use a bulky yarn which is not produced under the process described in the above-identified patent.

My invention resides in forming a pile fabric from this polymeric sheet material as it emerges from the foldingout step.

With reference to FIGURES 2 and 3, after the sheet material has been folded out as described hereinabove, it passes between a pair of generally cylindrical rollers 12 and 13, which are rotatably mounted in frame plates 14 and 16 respectively. These frame plates 14 and 16 extend vertically from a base plate 18 which is mounted on wheels 20. This unit is able to be wheeled into a position to receive the film 10 directly from the folding-out step described in FIGURE 1 in the event that it is desirable to make the whole process continuous. The sheet or web 10 passes from the rollers 12 and 13 to a roller 54 (see FIGURE 6) which is also rotatably mounted in plates 14 and 16.

With reference to FIGURE 6, a plurality of rollers 54 are shaped to form a crown 56 at their centers. As a result, the fibrils in the central portion of film 10 passing over the crown 56 will break while those in the edge portion of the film passing over the edge of the roller will not. This action of crowned rollers 54 (FIGURE 2) causes the fibrils in the center portion of sheet 10 to break. This web is particularly useful in making yarn and as such it is twisted by conventional yarn twisting means as it is wound onto a spool 58.

As shown in FIGURES 2 and 3, rollers 13, 54 (only one roller is shown; however, it would be within the skill of the art to connect a plurality of crowned rollers into the mechanism) and 29 are connected to a suitable driving mechanism 30. This mechanism comprises an endless belt or chain 32 which passes over a pulley or sprocket 34 which is fixed to roller 54, then over a sprocket 36 which is fixed to roller 13, then over a sprocket 38 which is fixed to roller 29, then over an idler sprocket 40, then over a drive sprocket 42, which is driven by any suitable power source such as electric motor 44, and finally back over sprocket 34. The rollers 12, 13, 54, 28, and 29 are rotated in the directions shown by the arrows.

With reference to FIGURE 4, roller 22 is provided with a plurality of grooves 24 and a plurality of needles 26- or other similar sharp, pointed implements, which project radially from the center of the grooves 24. These needles may be secured in the grooves 24 in any suitable manner. As the sheet 10 passes over the roller 22, portions of it are channelled into the grooves 24 and become impaled upon the needles which penetrate through the sheet material and cause a portion of the individual fibrils to be severed. The degree of breakage would be determined by the number of grooves in the roller and the number of pins in the grooves; however, no more than one-half of the fibers passing over the roller should be broken in order to retain sufiicient web strength. In the preferred embodiment we show only one roller but it would be within the skill of the art to adapt a plurality of rollers over which the film could be passed. The film after passing over the pin-studded roller 22 is received by a pair of pick-up rollers 28 and 29 which are also rotatably mounted in the frame plates 14 and 16. These rollers feed the bulky sheet material to a suitable take-up mandrel (not shown).

FIGURE 5 illustrates another embodiment of my invention. In this embodiment a roller 46 contains a plurality of grooves 48 around the perimeter thereof. These grooves are cut at an angle of 45 to the horizontal axis 50 of the roller 46. This roller 46 is attached to frames 14 and 16 in place of roller 22. A plurality of knife blades 52 are positioned around the circumference of roller 53 rotatably mounted between the vertical frames 14 and 16 a predetermined distance from roller 46. The sheet 10 is passed between the roller and the blade. The blade 52 is rotated in close enough proximity to the roller 46 so that portions of the film 10 pass over the crown of the grooves 48 and are cut by the rotating blades 52. Because of the angle of inclination of these grooves a discontinuous chopping of the individual fibrils results without cutting entirely across the sheet itself. The strength of the sheet itself is not significantly affected. This fabric possesses a tremendous advantage over a normal pile fabric because the pile fibers form an integral part of the sheet and are firmly anchored to the surface of the sheet.

In order to illustrate with greater particularity and clarity the operation of my process, the following examples are offered as illustrative of the operation thereof. The specific materials and conditions given in the examples are presented as being typical and should not be construed to limit my invention unduly.

EXAMPLE I A 60-inch wide fibrillated web of 0.8 mil polyethylene, having a density of 0.95 gram/cc. and a melt index of 0.3 (ASTM D 123 8-5DT, Condition E), is threaded through the machine described in FIGURE 2. A chopper roller 53 is provided with 12 tempered spring steel blades 52 around its circumference. The blades 52 coact with a 12-inch diameter grooved roller 46, made of mild steel and coated to a thickness of 60 mils with durometer rubber. Each groove 48 in roller 46 defines an ellipse in a plane making a 45 angle with the roller axis. These grooves are Aa-inch wide, Aa-inch deep, and spaced so that their centers are fli-inch apart, and having all their edges and corners chamfered and rounded on a -inch radius. Bulk film is fed to roller 12 at the rate of 20 feet per minute while the machine is being adjusted to insure clean, uniform cuts. After adjustment, the rate is increased to feet per minute and about 2000 feet of the material is fed through the machine.

Air filters 2 /2 feet square are produced from some of this material by laminating 21 layers of this bulked film together, each layer being laid at right angles to the adjacent layers 21 and being stitched together in both directions across the film at 6-inch intervals with cotton string and subsequently edged with an aluminum channel having a As-inch flange.

In another application ten 8-foot sections of this bulked fibrilated web are stitched together on 4-inch centers both lengthwise and crosswise and the edges bound to make an exceptionally warm, lightweight blanket.

Example 11 The rollers 46 and 53 are replaced with a 12-inch diameter pin-studded roller 22 similar to that shown in FIGURE 4. The grooves 24 are /2-inch center-to-center with a sharp 60 included angle peak between the grooves. In each groove 36 equally spaced cylindrical pins 26 are positioned wherein each pin is 7 -inch in diameter and has a flat, sharp edged top portion located -inch below the peaks. Web material similar to that used in Example I is threaded through the machine and the machine is started and run at an initial rate of about 15 feet per minute output while adjustments of the film tension over the pinstudded roller 22 are made. After adjustment, the rate is increased to 150 feet per minute to produce approximately raised to 375 p.s.i. The temperature is then raised to 300 C. Titanium dioxide is added as described for the A polymer. The pressure is then reduced to atmospheric over a 90-minute period while the temperature is raised to 320 C. The polymer is held with a nitrogen sweep at this temperature for 1 hour and then extruded and cut to flake in the conventional manner.

Polymers A and B are melted separately in screw-type melters at temperatures of 290 and 320 C. respectively and extruded simultaneously as described in Example 1 at 306 C. to form 34 trilobal filaments. The relative viscosity (measured with 5.5 grams of polyamide in 50 ml. of 98% formic acid) of the filaments containing 55% tt isomer is 56.7 while that of the 70% tt filaments is 39.4. The filaments from the two polymers are quenched and passed over a finish applicator roll where a conventional lubricating finish is applied. The filaments are then wound into a package at 750 y.p.m.

The yarn is drawn and given a hot annealing treatment as follows: The yarn passes from the supply package around the feed rolls and then is given 5 passes around a first heating element, which is heated to a temperature of 120 C. After the hot plate, the yarn is given five passes around an unheated draw roll and associated separator roll, the draw roll having a peripheral speed of 454 y.p.m. sufiicient to draw the yarn to a ratio of 2.43. From the draw roll the yarn passes to another roll having the same peripheral speed as the draw roll Where it passes 5 times around this roll and an associated separator roll and heating element, the heating element being at a temperature of 175 C. From this roll the yarn passes to a third roll having the same peripheral speed as the draw roll where it passes 5 times around this roll and an associated separator roll and heating element, the heating element being at a temperature of 175 C. From this roll the yarn passes to a fourth roll having the same peripheral speed where it is given two turns around the roll and its associated separator roll to permit the yarn to cool before being wound into the package.

The denier of the final yarn is 66. The yarn shrinkage under a load of 4 mg.d. in boiling Water is 9% while the DFL is 6.2%.

When the yarn is woven into a plain weave fabric and given a fabric finishing treatment involving relaxed scouring and heat-setting as in Example 1, the resulting fabric is found to be much superior to similar fabrics of mixed shrinkage 66 nylon yarn in regard to wash-wear characteristics, bulk, covering power and aesthetics.

Example 5 A 26-denier, 10 filament yarn contain ng 5 trilobal high shrinkage and 5 trilobal low shrinkage filaments is prepared following substantially the same procedure as described in Example 3 except that the draw ratio is 2.7 and the spinning speed is 465 yds./min. The molecular weight of the 45 tt filaments is 17,500 while that of the 80 tt filaments is 10,900. The DFL is 3.0%. The yarn is processed into a long float tricot knit fabric of 64 wales and 50 courses. The fabric is scoured in boiling water and then dried. The fabric is then heat-set in a relaxed state at 190 C. for seconds. The fabric bulk is 6.18 cc./gram as compared to 3.76 cc./gram for a 30-denier, 10 filament commercial nylon tricot fabric of 60 wales and 58 courses which was finished in identical fashion.

Example 6 Following the general procedure of Example 3, a 45 tt isomer polymer having a relative viscosity of 40.2 and an 80 tt isomer polymer having a relative viscosity of 23.9 are prepared. The polymers are cos-pun as described in Example 4 to form a 10 filament yarn which is then wound into a package in the conventional manner. The yarn is then cold drawn over a pin on a draw winder at a draw ratio of 2.35. From the draw roll, the yarn is passed to another power-driven roll and an associated separator roll, there being a C. heated shoe located between the power-driven roll and separator roll to contact the yarn as it passes around the two rolls. The yarn is given 5 wraps around these rolls, then passed to another powerdriven roll, and then wound into a package at a speed of 450' yds./min. The average DFL for the yarn is 4.1%. Proceeding as in Example 5, the yarn is processed into a tricot knit fabric, scoured and dried. Samples of the fabric are then heat-set in a relaxed state at various temperatures for 20 seconds. At C., the bulk is 5.8 cc./ gram, while at 192 C. the bulk has increased to 6.65 cc./gram.

Example 7 A homopolymer is prepared in an autoclave containing 40 parts water and 60 parts of the salt of bis-(4-aminocyclohexyl)methane and dodecanedioic acid. The diamine contains 70% of the tt isomer.-

As a viscosity stabilizer, 12 millimoles of acetic acid are added for each mole of the polyamide salt. The solution also contains 0.005% manganous hypophosphite, based on the weight of the salt. This solution is heated under 350 p.s.i. for 2 hrs. while the temperature is raised. Heating is continued and a sufficient amount of finelydivided kaolinite is added when the temperature reaches 200 C. to provide a concentration of 5% by weight of the kaolinite in the final polymer. The pressure is then reduced to atmospheric while the temperature is raised to 315 C. and the polymer held under nitrogen for 3 hrs. During this period, nitrogen ispassed through the autoclave at a low rate to remove additional water. It is then extruded and cut to flake. The relative viscosity of the flake is 29.9.

In a similar fashion, a copolymer (A) is prepared from a salt of dodecanedioic acid and a mixture of 70% tt bis- (4-aminocyclohexyl)methane and meta-xylylenediamine. The mixed diamines contain 8.1% by weight of metaxylylenediamine, which is sufiicient to provide 10% by weight of 11.90 mol percent of the corresponding polymer units in the final copolymer. Sutficient finely-divided kaolinite is added during polymerization to provide a concentration of 2% by weight of the polymer. The relative viscosity of the flake is 43.1.

Similarly, another copolymer (B) is prepared from the salt of dodecanedioic acidand a mixture of 70% tt bis- 4-aminocyclohexyl)methane and hexamethylenediamine. The mixed diamines contain 11.3% by weight of hexamethylenediamine, which is sufficient to provide 15% by Weight or 18.8 mol percent of the corresponding polymer units in the final copolymer. Sulficient finely-divided kaolinite is added during polymerization to provide 2% by weight of the polymer. The relative viscosity of the flake is 46.2.

The homopolymer and the copolymer from dodecanedioic acid and the mixture of bis-(4-aminocyclohexyl) methane and meta-xylylenediamine are melted separately and extruded as in Example 1 to form a mixture of 17 round cross-section homopolymer filaments and 17 round cross-section copolymer filaments. The spinnert face is blanketed with steam at 250 C. The filaments are processed as in Example 1 except that the interlacing step is omitted and the feed roll speed is 1349 y.p.m., the draw roll speed 3000 y.p.m., the annealling roll speed 2804 y.p.m. at the temperature indicated in Table 1 and the final unheated roll speed is 2870 y.p.m. The yarn is wound into a package at 2805 y.p.m. and the denier of the final yarn is 60. The relative viscosity of the homopolymer after extrusion is 31 and that of the copolymer is 44.8.

A 60 denier yarn containing a mixture of 17 homopolymer filaments and 17 copolymer filaments is prepared from the homopolymer and the copolymer prepared from the mixture of bis-(4-aminocyclohexyl)methane and 'hexamethylenediamine and dodecanedioic acid following the procedure outlined above except that the speed of the final unheated rolls is 2848 y.p.m. and the winding speed Portions of this salt are placed in heavy walled glass polymer tubes. The tubes are flushed with nitrogen, evacuated, sealed, and heated for 2 hrs. at 250 C. The tubes are then opened and the solid from each tube transferred to a large test tube fitted with a stopper containing an inlet tube. The tube is then heated in a steam atmosphere at 305 C. for 2 or 3 hrs. The polymers from the various tubes are then combined. The relative viscosity of the combined polymer is 60.1.

To 189 g. of the above salt is added 21 g. of the salt of bis-(4-aminocyclohexyl)methane and isophthalic acid. The latter salt is prepared by adding a solution of 42.8 g. of 70% tt bis-(4-aminocyclohexy1)methane in about 200 ml. of isopropanol to 33.2 g. of isophthalic acid in about 1500 ml. of isopropanol, filtering off the salt and drying at 70 C. under vacuum. The salts are thoroughly blended together and the mixture placed in glass polymer tubes. The tubes are heated at 280300 C. for about 2 hrs. The tubes are then opened and the solid from each tube transferred to a larger test tube fitted with a stopper containing an inlet tube. The polymerization is then completed by heating this material in a steam atmosphere for 2 hrs. at 325 C. The combined polymer from these tubes has a relative viscosity of 50.7. Based on the relative amounts of salts employed, the copolymer prepared in this manner should contain 10% by weight of the isophthalic polymer units. Following the procedure of Example 9, the above-prepared homopolymer and copolymer are melted separately and extruded from the same spinneret to form 34 filaments, 17 filaments from each of the polymers. The filaments are processed in accordance with Example 11, except that the temperature of the hot shoe between the draw roll andseparator roll is 140 C. and the draw pin temperature is 65 C. The denier of the final yarn is 130. The relative viscosity of the polymer after extrusion, as measured on the extruded filaments, is 95.8 for the homopolymer and 83.9 for the copolymer. The shrinkage and DFL of the yarn after ;bo iling in water under a load of 4 mg.d. are 9.7% and 3.7%, respectively. After boiling and under a load of 4 mg.d. and heat-setting under the same total load, the shrinkage is 18.7% and the DFL is 6.3%.

Example 13 A polymer prepared from the salt of 70% tt bis-(4- aminocyclohexyl)methane and dodecanedioio acid is extruded to form 34 trilobal cross-section filaments, and the filaments quenched following substantially the procedure of Example 7. The relative viscosity of the polymer flake prior to extrusion is 86.5 and the spinneret face is blanketed with steam at 160 C. After quenching, the filaments are passed for 6 wraps around a pair of feed rolls rotating at a peripheral speed of 1150 y.p.m. On leaving the feed rolls, the filaments are separated into two bundles of 17 filaments. One filament bundle is passed to and around a 1% inch tube heated to 120 C., then to a pair of 150 C. draw rolls rotating at a peripheral speed of 1435 y.p.m., then to a pair of unheated rolls rotating at a peripheral speed of 1425 y.p.m. The other filament bundle is passed from the feed rolls to and around a 6-inch drum heated to 120 C., then to a pair of 180 C. draw rolls rotating at 1410 y.p.m. From the draw rolls the filaments are passed to the unheated rolls, referred to above, where they are combined with the first group of filaments and given 8 wraps around these rolls. The combined filament bundle is then passed successively through two interlacing jets of the type described by Dahlstrom and Wert in their US. Patent No. 3,069,836, the air flow of the two jets being in opposite directions. The yarn is then wound into a package in the conventional manner at 1390 y.p.m. The crystalline orientation index of the filaments, measured as previously described, is 1.60 for the high shrinkage filaments, i.e., those heated at 150 C., and 2.86 for the low shrinkage filaments.

at 177 C., the shrinkage is 10.3% and the DFL 4.6%.

YARN PREPARATION The yarns of this invention may be prepared by mixing the high and low shrinkage filaments as described in the examples or, if desired, the high and low shrinkage filaments may be extruded from diflerent spinnerets and combined as they pass over a finish roll or by other suitable means. Alternately, the filaments may be intermingled by passing them through an air jet or other device where they are subjected to the action of a turbulent fluid which interlaces and intermingles the filaments.

The filaments may be of round or non-round shape as desired, but generally it is preferable to use non-round filaments such as the multilobal and shield shapes of US. 2,939,201 and US. 2,939,202.

It is frequently desirable that the yarns of this invention contain a durable antistatic agent. The antistatic agent should generally be present in a concentration of at least 2% by weight of the filament and may be added to either or both of the polymeric compositions used in producing these yarns. Suitable antistatic agents include the high molecular weight poly(alkylene ethers), i.e., those in the molecular weight of 1300 to 200,000. Agents of this type which may be used are described in Britain Patent No. 963,320. The yarns of this invention may also contain suitable heat stabilizers, antioxidants, light stabilizers, ultraviolet light absorbers, delustrants, pigments, dyes, and the like. Other polymer additives may be present to improve dyeability, soil repellence, crease resistance, hand, water repellence, wickability, strength, elongation, modulus, static propensity, or melting point of the fiber.

THE DRAWING STEP The draw ratios employed with the yarns of this invention tend to be somewhat lower than those employed with yarns prepared from polymers such as 6 or 66. Draw ratios in the range of about 1.4 to 3.0 may be employed to produce satisfactory yarns, the exact ratio selected depending on the polymer viscosity and the spinning speed, the ratio being low when the viscosity and spinning speed are relatively high. The yarns may be cold drawn or may be hot drawn at temperatures up to -180 C. with satisfactory results. Application of heat in the drawing zone is not essential but is frequently desirable to reduce the drawing tension.

SHRINKAGE CONTROL OF YARN Since it usually desirable in the preparation of fabrics that the shrinkage of the yarn in boiling water be relatively low, i.e., about li2l4% or lower, some heat treatment after drawing is usually required. To accomplish this, the yarn may be run over a series of heated rolls, hot plates, or other suitable heating elements. Where heated rolls of the type described in the examples are employed, temperatures in the range of l10160 C. are usually adequate to achieve the desired reduction in yarn shrinkage. The exact temperature must, of course, be chosen depending on such variables as polymer viscosity, isomer content, copolymer compositions, etc. In passing the yarn over the heated rolls, it is desirable to keep the tension at a relatively low level and, consequently, if the yarn tends to shrink, the relative speeds of the rolls are adjusted to permit this shrinkage while maintaining a low tension on the yarn.

Where a dilferential shrinkage yarn is prepared from a single polymer by processing the two groups of filaments differently, higher roll temperatures 180 C. and above, may be desirable for the low shrinkage filaments. In general, differential shrinkage yarns may be prepared from a single polymer by processing two groups of filaments in such a manner as to produce a lower orientation in mild mechanical treatment may, for instance, consist of striking, rubbing, brushing, or vibrating. Such treatment during the electrical treatment will not only fold out but also spread the material out.

At this point in the flow sheet of FIGURE 1 the sheet material is in a spread-out condition wherein the individual fibrils, making up the material, are parallel to the longitudinally axis of the sheet material. In many cases, and for many applications, this is a desirable configuration. However, for certain textile products the yarn used in the manufacture therein should not be lean and smooth but rather should have a high percentage of loose-fibrils along the surface of the web or sheet as the case may be. For instance, in the case of blankets, carpets, and fabrics made from woolen yarns, it is essential to use a bulky yarn which is not produced under the process described in the above-identified patent.

My invention resides in forming a pile fabric from this polymeric sheet material as it emerges from the foldingout step.

With reference to FIGURES 2 and 3, after the sheet material has been folded out as described hereinabove, it passes between a pair of generally cylindrical rollers 12 and 13, which are rotatably mounted in frame plates 14 and 16 respectively. These frame plates 14 and 16 extend vertically from a base plate 18 which is mounted on wheels 20. This unit is able to be wheeled into a position to receive the film 10 directly from the folding-out step described in FIGURE 1 in the event that it is desirable to make the whole process continuous. The sheet or web 10 passes from the rollers 12 and 13 to a roller 54 (see FIGURE 6) which is also rotatably mounted in plates 14 and 16.

With reference to FIGURE 6, a plurality of rollers 54 are shaped to form a crown 56 at their centers. As a result, the fibrils in the central portion of film 10 passing over the crown 56 will break while those in the edge portion of the film passing over the edge of the roller will not. This action of crowned rollers 54 (FIGURE 2) causes the fibrils in the center portion of sheet 10 to break. This web is particularly useful in making yarn and as such it is twisted by conventional yarn twisting means as it is wound onto a spool 58.

As shown in FIGURES 2 and 3, rollers 13, 54 (only one roller is shown; however, it would be within the skill of the art to connect a plurality of crowned rollers into the mechanism) and 29 are connected to a suitable driving mechanism 30. This mechanism comprises an endless belt or chain 32 which passes over a pulley or sprocket 34 which is fixed to roller 54, then over a sprocket 36 which is fixed to roller 13, then over a sprocket 38 which is fixed to roller 29, then over an idler sprocket 40, then over a drive sprocket 42, which is driven by any suitable power source such as electric motor 44, and finally back over sprocket 34. The rollers 12, 13, 54, 28, and 29 are rotated in the directions shown by the arrows.

With reference to FIGURE 4, roller 22 is provided with a plurality of grooves 24 and a plurality of needles 26- or other similar sharp, pointed implements, which project radially from the center of the grooves 24. These needles may be secured in the grooves 24 in any suitable manner. As the sheet 10 passes over the roller 22, portions of it are channelled into the grooves 24 and become impaled upon the needles which penetrate through the sheet material and cause a portion of the individual fibrils to be severed. The degree of breakage would be determined by the number of grooves in the roller and the number of pins in the grooves; however, no more than one-half of the fibers passing over the roller should be broken in order to retain sufiicient web strength. In the preferred embodiment we show only one roller but it would be within the skill of the art to adapt a plurality of rollers over which the film could be passed. The film after passing over the pin-studded roller 22 is received by a pair of pick-up rollers 28 and 29 which are also rotatably mounted in the frame plates 14 and 16. These rollers feed the bulky sheet material to a suitable take-up mandrel (not shown).

FIGURE 5 illustrates another embodiment of my invention. In this embodiment a roller 46 contains a plurality of grooves 48 around the perimeter thereof. These grooves are cut at an angle of 45 to the horizontal axis 50 of the roller 46. This roller 46 is attached to frames 14 and 16 in place of roller 22. A plurality of knife blades 52 are positioned around the circumference of roller 53 rotatably mounted between the vertical frames 14 and 16 a predetermined distance from roller 46. The sheet 10 is passed between the roller and the blade. The blade 52 is rotated in close enough proximity to the roller 46 so that portions of the film 10 pass over the crown of the grooves 48 and are cut by the rotating blades 52. Because of the angle of inclination of these grooves a discontinuous chopping of the individual fibrils results without cutting entirely across the sheet itself. The strength of the sheet itself is not significantly affected. This fabric possesses a tremendous advantage over a normal pile fabric because the pile fibers form an integral part of the sheet and are firmly anchored to the surface of the sheet.

In order to illustrate with greater particularity and clarity the operation of my process, the following examples are offered as illustrative of the operation thereof. The specific materials and conditions given in the examples are presented as being typical and should not be construed to limit my invention unduly.

EXAMPLE I A 60-inch wide fibrillated web of 0.8 mil polyethylene, having a density of 0.95 gram/cc. and a melt index of 0.3 (ASTM D 123 8-5DT, Condition E), is threaded through the machine described in FIGURE 2. A chopper roller 53 is provided with 12 tempered spring steel blades 52 around its circumference. The blades 52 coact with a 12-inch diameter grooved roller 46, made of mild steel and coated to a thickness of 60 mils with durometer rubber. Each groove 48 in roller 46 defines an ellipse in a plane making a 45 angle with the roller axis. These grooves are Aa-inch wide, Aa-inch deep, and spaced so that their centers are fli-inch apart, and having all their edges and corners chamfered and rounded on a -inch radius. Bulk film is fed to roller 12 at the rate of 20 feet per minute while the machine is being adjusted to insure clean, uniform cuts. After adjustment, the rate is increased to feet per minute and about 2000 feet of the material is fed through the machine.

Air filters 2 /2 feet square are produced from some of this material by laminating 21 layers of this bulked film together, each layer being laid at right angles to the adjacent layers 21 and being stitched together in both directions across the film at 6-inch intervals with cotton string and subsequently edged with an aluminum channel having a As-inch flange.

In another application ten 8-foot sections of this bulked fibrilated web are stitched together on 4-inch centers both lengthwise and crosswise and the edges bound to make an exceptionally warm, lightweight blanket.

Example 11 The rollers 46 and 53 are replaced with a 12-inch diameter pin-studded roller 22 similar to that shown in FIGURE 4. The grooves 24 are /2-inch center-to-center with a sharp 60 included angle peak between the grooves. In each groove 36 equally spaced cylindrical pins 26 are positioned wherein each pin is 7 -inch in diameter and has a flat, sharp edged top portion located -inch below the peaks. Web material similar to that used in Example I is threaded through the machine and the machine is started and run at an initial rate of about 15 feet per minute output while adjustments of the film tension over the pinstudded roller 22 are made. After adjustment, the rate is increased to 150 feet per minute to produce approximately 17 ments in the steric configuration of the diamino constituent by at least 10% by weight in a steric form.

7. A yarn consisting essentially of two groups of continuous oriented polycarbonamide filaments of different shrinkage, the first group of said filaments being constituted by a polycarbonamide wherein at least 50 mol percent of the repeating units are of the formula:

wherein x is 1 or 2, y is an integer in the range of 7-14, R is the same or difierent member of the class consisting of hydrogen and methyl, and the second group of said filaments being constituted by a polycarbonamide consisting essentially of the units of Formula I and having a relative viscosity that is at least about 9 units less than that of the polycarbonamide constituting the said first group of filaments.

8. A yarn consisting essentially of two groups of continuous oriented polycarbonamide filaments of different shrinkage, the first group of said filaments being constituted by a polycarbonamide wherein at least 50 mol percent of the repeating units are of the formula:

H R H 0 1@ t t t c.... t

I S I wherein x is 1 or 2, y is an integer in the range of 714,

R is the same or different member of the class consisting of hydrogen and methyl, and the second group of said filaments being constituted by a polycarbonamide consisting essentially of the units of Formula I wherein the chain length of the diacid constituent of the polymer units constituting the said second group of filaments is less than the chain length of the diacid constituent of the polymer units constituting the said first group of filaments.

9. A yarn consisting essentially of two groups of continuous oriented polycarbonamide filaments of diiferent shrinkage, the first group of said filaments being constituted by a polycarbonamide where at least 50 mol percent of the repeating units are of the formula:

H r r r t R X R R wherein x is 1 or 2, y is an integer in the range of 7-14, R is the same or different member of the class consisting of hydrogen and methyl, and the second group of said filaments being constituted by a polycarbonamide consisting essentially of the units of Formula I, the said second group of filaments having an Orientation Index that is at least about 1.0 greater than that of said first group of filaments.

10. The yarn of claim 4 wherein x is 1, y is 7 and R is hydrogen.

11. The yarn of claim 4 wherein x is 1, y is 10 and R is hydrogen.

12. The yarn of claim 6 wherein x is 1, y is 7 and R is hydrogen.

13. A yarn consisting essentially of two groups of continuous oriented polycarbonamide filaments of different composition and diflFerent shrinkage, the first group of said filaments being constituted by a polycarbonamide wherein at least 50 mol percent of the repeating units are of the formula:

wherein x is 1 or 2, y is an integer in the range of 7-14, R is the same or different member of the class consisting of hydrogen and methyl, and the second group of said filaments being constituted by a copolyamide containing from 50 to mol percent of the repeating units of Formula I and 5 to 50 mol percent of another polyamide unit prepared from a member of the class consisting of (1) the same diamine as employed for production of Formula I repeat unit with a different dicarboxylic acid and (2) the same dicarboxylic acid as employed for production of the Formula I repeat unit with a ditferent diamine, said yarn exhibiting a DFL greater than 1.0% after being subjected to a load of 4 mg.d. during boil-01f and increasing at least 0.5% in DFL after being subjected to heat-setting at 177 C. for two minutes under the same total load.

14. The yarn of claim 13 wherein each of said first and second groups of filaments is present to the extent of at least 25% by weight of the yarn.

15. The yarn of claim 13 consisting essentially of said first and second groups of filaments, wherein about 5% by weight of the diamino constituent of the repeating units of Formula I in both of said groups of filaments is in the cis-cis configuration and at least 50% by Weight of the repeating units of one of said groups is in the trans-trans configuration.

16. The yarn of claim 13 wherein the yarn increases at least 2% in DFL after being subjected to the heatsetting.

17. The yarn of claim 6 consisting essentially of said first and second groups of filaments, wherein about 5% by weight of the diamino constituent of the repeating units of Formula I in both of said groups of filaments is in the cis-cis configuration and at least 50% by Weight of the repeating units of one of said groups is in the transtrans configuration.

18. The yarn of claim 17 wherein each of said first and second groups of filaments is present to the extent of at least 25 by weight of the yarn.

19. The yarn of claim 7 consisting essentially of said first and second groups of filaments, wherein about 5% by weight of the diamino constituent of the repeating units of Formula I in both of said groups of filaments is in the cis-cis configuration and at least 50% by weight of the repeating units of one of said groups is in the trans-trans configuration.

20. The yarn of claim 19 wherein each of said first and second groups of filaments is present to the extent of at least 25 by weight of the yarn.

21. The yarn of claim 8 consisting essentially of said first and second groups of filaments, wherein about 5% by weight of the diamino constituent of the repeating units of Formula I in both of said groups of filaments is in the cis-cis configuration and at least 50% by weight of the repeating units of one of said groups is in the trans-trans configuration.

22. The yarn of claim 21 wherein each of said first and second groups of filaments is present to the extent of at least 25 by weight of the yarn.

23. The yarn of claim 9 consisting essentially of said first and second groups of filaments, wherein about 5% by weight of the diamino constituent of the repeating units of Formula I in both of said groups of filaments is in the cis-cis configuration and at least 50% by weight of the repeating units of one of said groups is in the trans-trans configuration.

24. The yarn of claim 23 wherein each of said first and second groups of filaments is present to the extent of at least 25% by weight of the yarn.

25. The yarn of claim 1 wherein said high and low shrinkage groups of filaments are each present to the extent of at least 25% by weight of the yarn.

26. The yarn of claim 25 consisting essentially of said high and low shrinkage groups of filaments. 

